The Factory letter refers to mine as a 1905 4th, Military Production. Serial #764871. Shipped 4/10/41 to Stone & Webster, Elwood, IL. One of 75 for the Kankakee Ordnance Works. 5", 38 SPL, absolutely no extra markings. Not sand-blasted, but very dull black, assume Black Magic. No wear, but appears someone bled on it. Secured through a firm that dealt in LE acquisitions.